DISEASE/DRUG OF INTEREST: Tetanus and Erythromycin
MOTIVATION AND BACKGROUND: Tetanus, also known as “lockjaw,” is caused by the bacteria Clostridium tetani which is present in soil, animal manure, and saliva.[1] The disease manifests itself through muscle stiffness in the jaw and other parts of the body. Clostridium bacteria germinates and produces a neurotoxin called Tetanospasmin, which affects the central nervous system and brain.[2] Many patients do not die from the infection itself, but rather from inhibited breathing and the inability to eat or drink.[3] Tetanus is most likely to occur in older people and low class agricultural workers (many of which are exposed to soil and cutting equipment) who are less likely to become vaccinated. Transmission of the disease during birth is also present in developing countries with unvaccinated mothers.[3] The primary method of transmission is through a deep cut or puncture wound that gets infected with the organism, rather than from person to person. It has also been seen in intravenous drug use and improper surgical procedures.[3] The first symptom is tightness of the jaw, followed by abdominal stiffness, spasms, and difficulties in breathing and swallowing. Other symptoms include sweating, fever, and hot/cold flashes.
The incubation period for tetanus is around one week but varies widely with the extent of infection and wound size. Complications include spasms of the vocal cords which make communication impossible, fractured bones from seizures and tight muscles, and elevated blood pressure coupled with heart abnormalities.[3] Treatment involves two different steps – administration of Tetanus ImmnoGlobulin (TIG) to neutralize free toxins, and the use of antibiotics, mainly erythromycin, to completely eliminate the source of infection.[3]
TARGET INFORMATION: Clostridium tetani is a Gram-positive bacterium that, like many prokaryotes, uses the 23S rRNA protein in the 50S subunit of ribosomes to thrive.This protein is responsible for both bacterial life processes and the production of the neurotoxin Tetanospasmin.[4] rRNA plays an important role in function of peptidyl transferase, the catalytic center of the ribosome responsible for the peptide bond formation and translation. It facilitates the binding of tRNA which brings amino acids to the ribosome for peptide bond synthesis.[5] rRNA is expressed according to the demand of bacteria for proteins, and in this case, neurotoxin. In prokaryotes, the 23S rRNA is part of the large subunit (the 50S) that joins with the 30S small subunit to create the functional 70S ribosome. The ribosome is comprised of 3 RNAs: the 23S, the 16S and the 5S ribosomal RNAs. The 23S and the 5S associate with their respective proteins to make up the large subunit of the ribosome, while the 16S RNA associates with its proteins to make up the small subunit.[5] Erythromycin is prokaryote specific because humans do not have the 50S subunit in their ribosomes. The 23S rRNA protein is composed of 245 amino acids in Clostridium tetani and has a molecular weight of approximately 9.9X105 daltons.[6]
Figure 1: Prokaryotic ribosome depicting the 50S and 30S subunits.
The 23S rRNA would be located in the Peptidyl transferase center,
controlling the docking of tRNA molecules bringing amino acids.[7]
Figure 2: General bacterial process of exotoxin release.[8]
DRUG INFORMATION:
Erythromycin is an orally effective antibiotic discovered in 1952 in the metabolic products of a strain of Streptocyces erythreus, originally obtained from a soil sample. The drug is also known by the brand names Erythromycin A, Erymax, E-Mycin, Ilotycin, Emgel, erythro, Abomacetin, Erythromycinum, and Benzamycin.[9] Its molecular formula is C37H67NO13 and weight is 733.92678 g/mol. The CAS number is 114-07-8.[10] It is classified under the macrolides, or antibiotics derived from soil bacteria and effective against Gram-Positive strains. The macrolide family of antibiotics is characterized by structures that contain large lactone rings linked through glycoside bonds with amino sugars. Like any antiobiotic, It’s maximum effectiveness is only achieved if the bacteria responsible for the infection are correctly identified. Erythromycin and other macrolide antibiotics inhibit protein synthesis by binding to the 23S rRNA molecule (in the 50S subunit) of the bacterial ribosome blocking the exit of the growing peptide chain of sensitive microorganisms. (Humans do not have 50S ribosomal subunits, but have ribosomes composed of 40S and 60S subunits). Certain resistant microorganisms with mutational changes in this subunit of the ribosome fail to bind the drug. The association between erythromycin and the ribosome is reversible and takes place only when the 50S subunit is free from tRNA molecules carrying new amino acid chains. Gram-positive bacteria accumulate about 100 times more erythromycin than do gram-negative microorganisms. The non ionized form of the drug is considerably more permeable to cells.[11] This drug is available in the following dosage forms, although most cases of tetanus are treated by oral tablet or intravenous drip in severe cases:
Tablet, Delayed Release
Tablet, Enteric Coated
Capsule
Capsule, Delayed Release
Tablet
Suspension
Powder for Suspension
Tablet,Chewable
Side effects include:
Hearing problems
Severe dizziness
Mild diarrhea
Muscle weakness
Nausea or stomach pain
Night sweats
Pseudomembranous colitis is a potentially fatal condition when there is a large amount of harmful bacteria in the digestive tract.
Pyloric stenosis in infants
Vomiting
Yeast infections since erythromycin kills both good and bad bacteria.[11]
Alternatives to this drug include any other macrolide antiobiotics such as Azithromycin (Zithromax/Z-Pak), Clindamycin (Cleocin), Clarithromycin (Biaxin) Tetracycline (Diabecline), and Amoxicillin (Moxatag). Erythromycin is in high competition with Z-Pak due to its price and ability to combat a larger variety of pathogens. The drug itself is not patented but many of its derivatives like spiramycin and nystatin are. Although there are no specific clinical trials depicting erythromycin and Clostridium tetani, there have been many other trials using azithromycin, a close macrolide, and other infectious diseases. Azithromycin, a newer macrolide drug, was found to be active in-vitro against V. cholerae, has a long half-life, and is better tolerated than erythromycin, an older macrolide.[12]
Erythromycin is used to treat acute pelvic inflammatory disease, diphtheria, erythrasma, whooping cough, listeriosis, and intestinal amebiasis. It is used for the treatment of staphylococcal infections of the skin and as an alternative antibiotic for the treatment of syphilis, gonorrhea, and chlamydia, and other bacterial STDs. Erythromycin is used in patients who are allergic to penicillin for the prevention of infections of the hearts' valves (endocarditis). The non-FDA approved uses for erythromycin include acne and Lyme disease.[13
Makers of the drug in the US include Akorn, Healthpoint, Hoechst Marion Roussel, Dermik, Del-Ray, Barr, Abbott, Fulton, Glaxo Wellcome, Protea, Janssen-Cilag, Dermol, Alra, Dista, Ocusoft, Westwood, Medicis, and Wyeth.[14]
Tetanus and Erythromycin
MOTIVATION AND BACKGROUND:
Tetanus, also known as “lockjaw,” is caused by the bacteria Clostridium tetani which is present in soil, animal manure, and saliva.[1] The disease manifests itself through muscle stiffness in the jaw and other parts of the body. Clostridium bacteria germinates and produces a neurotoxin called Tetanospasmin, which affects the central nervous system and brain.[2] Many patients do not die from the infection itself, but rather from inhibited breathing and the inability to eat or drink.[3] Tetanus is most likely to occur in older people and low class agricultural workers (many of which are exposed to soil and cutting equipment) who are less likely to become vaccinated. Transmission of the disease during birth is also present in developing countries with unvaccinated mothers.[3] The primary method of transmission is through a deep cut or puncture wound that gets infected with the organism, rather than from person to person. It has also been seen in intravenous drug use and improper surgical procedures.[3] The first symptom is tightness of the jaw, followed by abdominal stiffness, spasms, and difficulties in breathing and swallowing. Other symptoms include sweating, fever, and hot/cold flashes.
The incubation period for tetanus is around one week but varies widely with the extent of infection and wound size. Complications include spasms of the vocal cords which make communication impossible, fractured bones from seizures and tight muscles, and elevated blood pressure coupled with heart abnormalities.[3] Treatment involves two different steps – administration of Tetanus ImmnoGlobulin (TIG) to neutralize free toxins, and the use of antibiotics, mainly erythromycin, to completely eliminate the source of infection.[3]
TARGET INFORMATION:
Clostridium tetani is a Gram-positive bacterium that, like many prokaryotes, uses the 23S rRNA protein in the 50S subunit of ribosomes to thrive.This protein is responsible for both bacterial life processes and the production of the neurotoxin Tetanospasmin.[4] rRNA plays an important role in function of peptidyl transferase, the catalytic center of the ribosome responsible for the peptide bond formation and translation. It facilitates the binding of tRNA which brings amino acids to the ribosome for peptide bond synthesis.[5] rRNA is expressed according to the demand of bacteria for proteins, and in this case, neurotoxin. In prokaryotes, the 23S rRNA is part of the large subunit (the 50S) that joins with the 30S small subunit to create the functional 70S ribosome. The ribosome is comprised of 3 RNAs: the 23S, the 16S and the 5S ribosomal RNAs. The 23S and the 5S associate with their respective proteins to make up the large subunit of the ribosome, while the 16S RNA associates with its proteins to make up the small subunit.[5] Erythromycin is prokaryote specific because humans do not have the 50S subunit in their ribosomes. The 23S rRNA protein is composed of 245 amino acids in Clostridium tetani and has a molecular weight of approximately 9.9X105 daltons.[6]
Figure 1: Prokaryotic ribosome depicting the 50S and 30S subunits.
The 23S rRNA would be located in the Peptidyl transferase center,
controlling the docking of tRNA molecules bringing amino acids.[7]
Figure 2: General bacterial process of exotoxin release.[8]
DRUG INFORMATION:
Erythromycin is an orally effective antibiotic discovered in 1952 in the metabolic products of a strain of Streptocyces erythreus, originally obtained from a soil sample. The drug is also known by the brand names Erythromycin A, Erymax, E-Mycin, Ilotycin, Emgel, erythro, Abomacetin, Erythromycinum, and Benzamycin.[9] Its molecular formula is C37H67NO13 and weight is 733.92678 g/mol. The CAS number is 114-07-8.[10] It is classified under the macrolides, or antibiotics derived from soil bacteria and effective against Gram-Positive strains. The macrolide family of antibiotics is characterized by structures that contain large lactone rings linked through glycoside bonds with amino sugars. Like any antiobiotic, It’s maximum effectiveness is only achieved if the bacteria responsible for the infection are correctly identified. Erythromycin and other macrolide antibiotics inhibit protein synthesis by binding to the 23S rRNA molecule (in the 50S subunit) of the bacterial ribosome blocking the exit of the growing peptide chain of sensitive microorganisms. (Humans do not have 50S ribosomal subunits, but have ribosomes composed of 40S and 60S subunits). Certain resistant microorganisms with mutational changes in this subunit of the ribosome fail to bind the drug. The association between erythromycin and the ribosome is reversible and takes place only when the 50S subunit is free from tRNA molecules carrying new amino acid chains. Gram-positive bacteria accumulate about 100 times more erythromycin than do gram-negative microorganisms. The non ionized form of the drug is considerably more permeable to cells.[11] This drug is available in the following dosage forms, although most cases of tetanus are treated by oral tablet or intravenous drip in severe cases:Side effects include:
Alternatives to this drug include any other macrolide antiobiotics such as Azithromycin (Zithromax/Z-Pak), Clindamycin (Cleocin), Clarithromycin (Biaxin) Tetracycline (Diabecline), and Amoxicillin (Moxatag). Erythromycin is in high competition with Z-Pak due to its price and ability to combat a larger variety of pathogens. The drug itself is not patented but many of its derivatives like spiramycin and nystatin are. Although there are no specific clinical trials depicting erythromycin and Clostridium tetani, there have been many other trials using azithromycin, a close macrolide, and other infectious diseases. Azithromycin, a newer macrolide drug, was found to be active in-vitro against V. cholerae, has a long half-life, and is better tolerated than erythromycin, an older macrolide.[12]
Erythromycin is used to treat acute pelvic inflammatory disease, diphtheria, erythrasma, whooping cough, listeriosis, and intestinal amebiasis. It is used for the treatment of staphylococcal infections of the skin and as an alternative antibiotic for the treatment of syphilis, gonorrhea, and chlamydia, and other bacterial STDs. Erythromycin is used in patients who are allergic to penicillin for the prevention of infections of the hearts' valves (endocarditis). The non-FDA approved uses for erythromycin include acne and Lyme disease.[13
Makers of the drug in the US include Akorn, Healthpoint, Hoechst Marion Roussel, Dermik, Del-Ray, Barr, Abbott, Fulton, Glaxo Wellcome, Protea, Janssen-Cilag, Dermol, Alra, Dista, Ocusoft, Westwood, Medicis, and Wyeth.[14]
Figure 3: Chemical structure of Erythromycin.[15]
REFERENCES:
[1] National Library of Medicine. Tetanus: MedlinePlus. http://www.nlm.nih.gov/medlineplus/tetanus.html (accessed Feb 2, 2014)
[2] MicrobeWiki, The Student-Edited Microbiology Resource. Clostridium tetani and Tetanus. http://microbewiki.kenyon.edu/index.php/Clostridium_tetani_and_Tetanus (accessed Feb 2, 2014)
[3] New York Department of Health. Tetanus (lockjaw). http://www.health.ny.gov/diseases/communicable/tetanus/fact_sheet.htm (accessed Feb 2, 2014)
[4] Poudel, P.; Budhathoki, S.; Manandhar, S., Tetanus. Kathmandu Univ Med J (KUMJ) 2009, 7 (27), 315-22.
[5] Bocchetta, M.; Xiong, L.; Mankin, A. S., 23S rRNA positions essential for tRNA binding in ribosomal functional sites. Proc Natl Acad Sci USA 1998, 95 (7), 3525-30.
[6] National Center for Biotechnology Information, National Library of Medicine. 23S rRNA methyltransferase [Clostridium tetani]. http://www.ncbi.nlm.nih.gov/protein/WP_023439620.1 (accessed Feb 2, 2014)
[7] Williamson, J. R., Molecular biology. Small subunit, big science. Nature 2000, 407 (6802), 306-7.
[8] Midlans Technical Institute. BIO225, Chapter 15. http://classes.midlandstech.edu/carterp/Courses/bio225/chap15/FIGURE_15_05_LABELED.jpg (accessed Feb 2, 2014)
[9] Ophardt, C. Drug Action Virtual Chembook [Online] 2003. http://www.elmhurst.edu/~chm/vchembook/654antibiotic.html (accessed Feb 2, 2014)
[10] National Center for Biotechnology Information. PubChem Substance Databse; CID=12560, http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=12560&loc=ec_rcs (accessed Feb 2, 2014)
[11] Erythromycin.org Database. Erythromycin: What is it? And What does it do? http://erythromycin.org/erythromycin (accessed Feb 2, 2014)
[12] Saha, D.; Karim, M. M.; Khan, W. A.; Ahmed, S.; Salam, M. A.; Bennish, M. L., Single-dose azithromycin for the treatment of cholera in adults. N Engl J Med 2006, 354 (23), 2452-62.
[13] Medscape Drug Reference. Erythromycin Ethylsuccinate (Rx). http://reference.medscape.com/drug/ees-eryped-erythromycin-ethylsuccinate-999596 (accessed Feb 2, 2014)
[14] Antimicrobe Database; Infectious Disease and Antimicrobial Agents. “Drug Popup” http://www.antimicrobe.org/drugpopup/Erythromycin%20-%20Brand%20names.htm (accessed Feb 2, 2014)
[15] Todar, K. Antimicrobial Agents in the Treatment of Infectious Disease. Online Textbook of Bacteriology [Online] 2008 Chapter 24 pp. 4-6. http://textbookofbacteriology.net/antimicrobial_4.html (accessed Feb 2, 2014)